qml: report unified password change failure, impose minimum password length of 5, disallow empty passwords

electrum/gui/qml/components/PasswordDialog.qml

@@ -74,7 +74,7 @@ ElDialog {
             Layout.fillWidth: true
             text: qsTr("Ok")
             icon.source: '../../icons/confirmed.png'
-            enabled: confirmPassword ? pw_1.text == pw_2.text : true
+            enabled: confirmPassword ? pw_1.text.length > 4 && pw_1.text == pw_2.text : true
             onClicked: {
                 password = pw_1.text
                 passworddialog.accept()

electrum/gui/qml/components/WalletDetails.qml

@@ -508,18 +508,23 @@ Pane {
             app.stack.pop()
         }
         function onRequestNewPassword() { // new unified password (all wallets)
-            var dialog = app.passwordDialog.createObject(app,
-                    {
-                        'confirmPassword': true,
-                        'title': qsTr('Enter new password'),
-                        'infotext': qsTr('If you forget your password, you\'ll need to\
-                        restore from seed. Please make sure you have your seed stored safely')
+            var dialog = app.passwordDialog.createObject(app, {
+                confirmPassword: true,
+                title: qsTr('Enter new password'),
+                infotext: qsTr('If you forget your password, you\'ll need to restore from seed. Please make sure you have your seed stored safely')
             })
             dialog.accepted.connect(function() {
                 Daemon.setPassword(dialog.password)
             })
             dialog.open()
         }
+        function onPasswordChangeFailed() {
+            var dialog = app.messageDialog.createObject(app, {
+                title: qsTr('Error'),
+                text: qsTr('Password change failed')
+            })
+            dialog.open()
+        }
         function onWalletDeleteError(code, message) {
             if (code == 'unpaid_requests') {
                 var dialog = app.messageDialog.createObject(app, {text: message, yesno: true })
@@ -544,9 +549,9 @@ Pane {
         target: Daemon.currentWallet
         function onRequestNewPassword() { // new wallet password
             var dialog = app.passwordDialog.createObject(app, {
-                'confirmPassword': true,
-                'title': qsTr('Enter new password'),
-                'infotext': qsTr('If you forget your password, you\'ll need to restore from seed. Please make sure you have your seed stored safely')
+                confirmPassword: true,
+                title: qsTr('Enter new password'),
+                infotext: qsTr('If you forget your password, you\'ll need to restore from seed. Please make sure you have your seed stored safely')
             })
             dialog.accepted.connect(function() {
                 Daemon.currentWallet.set_password(dialog.password)

electrum/gui/qml/qedaemon.py

@@ -127,6 +127,7 @@ class QEDaemon(AuthMixin, QObject):
     newWalletWizardChanged = pyqtSignal()
     serverConnectWizardChanged = pyqtSignal()
     loadingChanged = pyqtSignal()
+    passwordChangeFailed = pyqtSignal()
 
     walletLoaded = pyqtSignal([str,str], arguments=['name','path'])
     walletRequiresPassword = pyqtSignal([str,str], arguments=['name','path'])
@@ -316,11 +317,10 @@ class QEDaemon(AuthMixin, QObject):
     @pyqtSlot(str)
     def setPassword(self, password):
         assert self._use_single_password
-        # map empty string password to None
-        if password == '':
-            password = None
-        self._logger.debug('about to set password for ALL wallets')
-        self.daemon.update_password_for_directory(old_password=self._password, new_password=password)
+        assert password
+        if not self.daemon.update_password_for_directory(old_password=self._password, new_password=password):
+            self.passwordChangeFailed.emit()
+            return
         self._password = password
 
     @pyqtProperty(QENewWalletWizard, notify=newWalletWizardChanged)